<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>iframe</title>
</head>
<body>

    <p>请查看控制台输出</p>
    
    <script>
        function isArray(obj) {
            return obj instanceof Array;
        }

        function isArray2(obj) {
            return Object.prototype.toString.call(obj).toLowerCase() === '[object array]';
        }

        function isArray3(obj) {
            return Array.isArray(obj);
        }
    </script>

</body>
</html>